Branches, Bifurcations and Retroflections over the Tail of the Grand Banks

大浅滩尾部的分支、分叉和反射

• 批准号: 0550423
• 负责人: Michael McCartney
• 金额: $ 49.99万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0550423&HistoricalAwards=false
• 关键词: Branches; Bifurcations; Retroflections; over; Tail

It is proposed to analyze existing data (hydrography, current meter, surface drifter, subsurface float, altimetric and SST observations), to characterize the mean and variable (mesoscale through seasonal to interannual) regional circulation around the Tail of the Grand Banks, ultimately enabling a more complete description of the branches, bifurcations and retroflections of the currents.This is a critical location for the North Atlantic circulation. There, major branches of the wind-driven (Gulf Stream and Labrador Current) and thermohaline circulations (Deep Western Boundary Current) meet, and dramatic changes in the character and pathways of the currents follow. The Labrador Current and Deep Western Boundary Current partially retroflect near the Tail of the Banks, but the amount of transport lost by the combined currents and the details of the retroflection pathway are unknown. Similarly, south of the Grand Banks, the Gulf Stream approaches the Tail from the west with full-depth flow carrying large transport. At the Tail, the Gulf Stream splits into four branches, with a critical branch turning north across the Tail to feed the North Atlantic Current east of the Grand Banks. The exact partitioning of transport into separate branches remains unknown. The interaction between the deep-reaching currents appears forced and constrained by the shoaling topography of the Tail, resulting in a regional distortion of the thermocline into a cyclonic meander over the Tail a trough - remarkably stable in both space and time. Based on existing observations we hypothesize that the trough configuration represents a bottleneck for the approaching currents, limiting the strengths of the current branches crossing the Tail. This will be a quantitative description within the limits of existing data, and may point to critical new measurements that would tighten the constraints on the characterization. The output from high-resolution numerical models will also be examined with the goal of gaining insight into the dynamics of the Tail-induced bottleneck.

建议分析现有数据（水文、海流计、表面漂流器、次表层浮标、高度和SST观测），以确定大浅滩尾部周围区域环流的平均值和变量（中尺度、季节性到年际），最终能够更完整地描述洋流的分支、分叉和回折，这是北大西洋环流的一个关键位置。在那里，风力驱动的主要分支（墨西哥湾流和拉布拉多海流）和温盐环流（深西部边界海流）相遇，海流的特征和路径随之发生巨大变化。拉布拉多电流和深西部边界电流部分retroflect附近的银行的尾部，但运输量损失的合并电流和retroflection途径的细节是未知的。同样，在大浅滩以南，墨西哥湾流从西部接近尾部，全深度流动携带大量运输。在尾部，墨西哥湾流分成四个分支，其中一个关键的分支转向北，穿过尾部，流入大浅滩以东的北大西洋海流。运输的确切划分仍然是未知的。深层电流之间的相互作用似乎被迫和约束的浅滩地形的尾巴，导致在区域扭曲的温跃层成气旋蜿蜒的尾巴槽-非常稳定的空间和时间。根据现有的观测结果，我们假设，槽配置是一个瓶颈的接近电流，限制了强度的电流分支穿过尾巴。这将是在现有数据范围内的定量描述，并可能指向关键的新测量，这将加强对表征的限制。高分辨率数值模型的输出也将进行检查，以深入了解尾部引起的瓶颈的动态。